Fig. 1

Intracerebroventricular administration of 0.45 μg/day siponimod attenuates EAE motor deficits without inducing peripheral lymphocyte depletion. a Schematic representation of the experimental design used in the study. Minipump implantation and siponimod/vehicle release preceded the induction of EAE by 1 week. All examinations were performed on animals during the peak of the symptomatic phase of the disease 18–24 dpi, both in the peripheral blood samples and in the striatum of the animals. b CD3⁺ lymphocytes were counted in the peripheral blood of EAE mice receiving vehicle or different siponimod dosages: significant reduction was observed for the 4.5 μg/day dosage. Siponimod 4.5 μg/day vs vehicle ##p < 0.01 unpaired T test; siponimod 0.45 μg/day vs vehicle p > 0.05 unpaired T test; siponimod 0.225 μg/day vs vehicle p > 0.05 unpaired T test. c Siponimod concentrations were determined in peripheral blood samples of EAE mice receiving intracerebroventricular release of different siponimod dosages: the highest concentration (4.5 μg/day) used was significantly higher compared to both 0.450 μg/day and 0.225 μg/day, while there were no statistically differences between the other two dosages. Tukey’s post hoc ***p < 0.001. d Representative clinical course of EAE mice treated with three different siponimod dosages: EAE disease progression is strongly affected by 4.5 μg/day dosage during the symptomatic phase of the disease and significantly attenuated by 0.45 μg/day concentration in the dpi range of 18–24. Daily statistical significance was evaluated by non-parametric Mann-Whitney test